1. Field of the Invention
The present invention relates generally to an image signal generating system. More particularly, the invention relates to a stroke-dot type image signal generating system for generating an electronic image signal for a character, sign or so forth for displaying on a display screen or for printing by a printer or so forth, of the character, sign or so forth processed by an information processing system, such as a computer or so forth.
2. Description of the Related Art
As systems for generating image signal for character, sign or so forth processed by an information processing system, such as a computer or so forth, dot system, stroke system and stroke-dot system have been conventionally known.
The dot system is also called as full-dot system and, in which a character pattern as an aggregate of dots is preliminarily prepared and stored. When a desired character is to be displayed or printed, the character pattern corresponding to the desired character is read out from a storage portion and output. In this dot system, the character patterns are required for difference sizes of the same character to require large capacity for storing the character patterns. The stroke system generates the character pattern, in which the contour of the character is approximated by straight lines.
The stroke-dot system generates the character pattern by generating the contour of the character based on a stroke information (contour information) and painting the inside of the contour by dots. This stroke-dot system permits generation of arbitrary sizes of character patterns by expansion and compression by storing stroke information of a predetermined size of character. Since this system requires storing only stroke information for the specific or predetermined size of character, the required storage capacity can be much smaller than that of the dot system.
The conventional image signal generating system employing this stroke-dot system drafts the contour of the desired character on a work memory on the basis of the stroke information of the corresponding character, and paints inside of the contour by raster scanning of the work memory on which contour drafting is performed to generate the painted data.
When a character pattern greater than the capacity of the work memory is to be generated, the character is divided into a plurality of drafting regions in a Y-axis direction so that contour is drafted for each drafting region, and then the inside of the contour is painted to produce the painted data. Thus, it becomes possible to generate the character pattern expanded in the Y-axis direction. However, the size of the drafting region in X-axis direction is limited within the physical size in the X-axis direction of the work memory so that a large capacity of the work memory is required for obtaining the character expanded in the X-axis direction. Namely, greater capacity of the work memory is required for greater size of the character to be generated. Accordingly, the system to generate the large character inevitably becomes expensive for the requirement of the greater capacity of the work memory.